Olk D C, Bloom P R, Perdue E M, McKnight D M, Chen Y, Farenhorst A, Senesi N, Chin Y-P, Schmitt-Kopplin P, Hertkorn N, Harir M
J Environ Qual. 2019 Mar;48(2):217-232. doi: 10.2134/jeq2019.02.0041.
To study the structure and function of soil organic matter, soil scientists have performed alkali extractions for soil humic acid (HA) and fulvic acid (FA) fractions for more than 200 years. Over the last few decades aquatic scientists have used similar fractions of dissolved organic matter, extracted by resin adsorption followed by alkali desorption. Critics have claimed that alkali-extractable fractions are laboratory artifacts, hence unsuitable for studying natural organic matter structure and function in field conditions. In response, this review first addresses specific conceptual concerns about humic fractions. Then we discuss several case studies in which HA and FA were extracted from soils, waters, and organic materials to address meaningful problems across diverse research settings. Specifically, one case study demonstrated the importance of humic substances for understanding transport and bioavailability of persistent organic pollutants. An understanding of metal binding sites in FA and HA proved essential to accurately model metal ion behavior in soil and water. In landscape-based studies, pesticides were preferentially bound to HA, reducing their mobility. Compost maturity and acceptability of other organic waste for land application were well evaluated by properties of HA extracted from these materials. A young humic fraction helped understand N cycling in paddy rice ( L.) soils, leading to improved rice management. The HA and FA fractions accurately represent natural organic matter across multiple environments, source materials, and research objectives. Studying them can help resolve important scientific and practical issues.
为了研究土壤有机质的结构和功能，土壤科学家们进行碱提取以获取土壤腐殖酸（HA）和富里酸（FA）组分已有200多年的历史。在过去几十年里，水生科学家们使用了类似的溶解有机质组分，通过树脂吸附然后碱解吸来提取。批评者声称，碱可提取组分是实验室产物，因此不适用于研究田间条件下天然有机质的结构和功能。作为回应，本综述首先解决了关于腐殖质组分的具体概念问题。然后我们讨论了几个案例研究，其中从土壤、水和有机材料中提取了HA和FA，以解决不同研究环境中的有意义问题。具体而言，一个案例研究表明腐殖质对于理解持久性有机污染物的迁移和生物有效性的重要性。事实证明，了解FA和HA中的金属结合位点对于准确模拟土壤和水中金属离子的行为至关重要。在基于景观的研究中，农药优先与HA结合，降低了它们的流动性。通过从这些材料中提取的HA的性质，可以很好地评估堆肥成熟度和其他有机废物用于土地施用的可接受性。一种年轻的腐殖质组分有助于理解水稻土中的氮循环，从而改善水稻管理。HA和FA组分准确地代表了多种环境、源材料和研究目标下的天然有机质。对它们进行研究有助于解决重要的科学和实际问题。
